Just half of VW's models have passed emissions certifications ahead of the September 1 deadline

But according to Volkswagen’s head of sales and marketing in Germany, Thomas Zahn, just seven out of 14 models sold in Europe were certified before the Saturday cut-off.

Zahn told journalists in a conference call last week that new testing could "take two to three times longer than in the past" - normal delivery takes two-three months, and four months for overseas deliveries.

The popular Golf is one of the variants yet to pass certification, which could leave thousands of customers frustrated as they wait for delivery of the UK's second-most popular car.

Zhan claims the full Golf range should have passed certification by the end of this month, but given the backlog of orders across the continent, customers will still be forced to wait months before they receive their car.

Volkswagen models yet to pass WLTP certification process

Customers could be waiting up to five months for delivery of new Golf models

Other Volkswagen Group manufacturers have also been affected by the delay.

According to Audi's website, the A1, A6 saloon and Avant and the A7 sportback all have certain engines approved under WLTP, while the majority of their models are waiting to be certified.

Seat and Skoda said they are restricted from releasing the names of models facing delays, while Porsche has suspended orders for its entire engine range.

A spokesperson for Volkswagen UK told Sun Motors today: "WLTP has resulted in a slight increase in delivery times for the Golf here in UK.

"Up from around six to 10 weeks pre-WLTP depending on specific model ordered to somewhere around 14-15 weeks."

A VW dealership told Sun Motors today that buyers could be waiting as long as five months for delivery on some Golf models.

Smaller engine models are likely to take up to 12 weeks to reach their new owners, but anything boasting an engine larger than 1.5-litres is likely to be delayed by closer to five months.

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According to the dealership, customers who purchased their car prior to May this year could be eligible for some compensation like a courtesy car while they wait for delivery, but new customers will simply have to sit tight until their model is ready.

VW allegedly attributed the delay to the 2015 emissions scandal, saying its engineers were focused on refitting cars to resolve the issue, and staff were too stretched to properly address the WLTP.

Earlier this year, VW announced it would halt production "one to two days per week" at its Wolfsburg factory throughout August and September as authorities were taking longer than expected to certify new cars under the WLTP.